1. Field of the Invention
The present invention relates to an apparatus for fixing rotary heads to a rotary drum of a video cassette recorder (VCR), in which two or four heads are mounted on the drum at intervals of 180.degree. or 90.degree..
2. Description of the Prior Art
Generally, a video cassette recorder is of a two-head type or a four-head type depending upon the number of rotary heads mounted on a rotary drum. In the case of the two-head type, the heads mounted on the drum are spaced from each other by 180.degree., while in the case of the four-head type, they are fixedly mounted on the drum at intervals of 90.degree.. The rotary head is a very important part of the video cassette recorder. It functions to record an image on a tape traveling in contact with the rotary drum or to reproduce an image recorded on a tape. Therefore, the rotary head must be precisely mounted on the rotary drum in order to obtain excellent picture quality.
In a prior art apparatus, as shown in FIGS. 1 through 3 of the accompanying drawings, the rotary heads (3) are fixedly mounted on the rotary drum (1) by placing an upper drum (2) of the type shown in FIG. 2a on a jig for temporary assembly of the rotary heads, then temporarily assembling the heads (3) to the upper drum (2) by means of set screws (4) for fastening the rotary heads, and thereafter adjusting a given angle between the rotary heads, an amount of protrusion of the heads, a height difference, etc. by a separate adjustor.
The height difference between the rotary heads may be adjusted by means of screws (7) which are threaded in the upper drum (2) to contact the lower surfaces of the rotary heads (3). Subsequently, leg relays (5) are assembled to the upper drum (2) and soldered to signal grounding portions (6) of the rotary heads (3). The completed assembly of the upper drum (2) has a configuration as shown in FIG. 2b.
Assembled upper drum (2) is then assembled to a lower drum (8) to produce the rotary drum (1) as shown in FIG. 1.
The prior art apparatus for fixing the rotary heads is however disadvantageous in that since the rotary heads are pressed down by a soldering iron during the operation of soldering the leg relays (5) to the signal grounding portions (6) of the rotary heads, the angle between the rotary heads which has already been adjusted by use of the separate adjustor prior to the soldering operation may be varied, thereby resulting in deterioration of picture quality, for example, distortion of an upper picture portion, flexure of a picture, a color band, et. Further, since the amount of protrusion of the rotary head is determined by fixing the rotary head to the upper drum by means of the set screw which is fastened through a pre-formed hole in the head into a threaded hole pre-formed in the drum, it is difficult to adjust the extent of protrusion after assembly of the rotary head. When the given protrusion of the head is not constantly maintained, it is necessary to form another hole for the set screw in the head or change the position of the threaded hole of the upper drum. However, since forming of the new holes is substantially impossible, the parts must be replaced, thereby adversely affecting the cost of the product.